Answer: The required value of c is 5.
Step-by-step explanation: We are given to Alessandro wrote the following quadratic equation in standard form.
We are to find the value of c in his new equation.
We know that
a quadratic equation can be written in standard form as follows :

So, the given equation can be written as :

Comparing with the standard form (i), we find that the value of c is 5.
That is, c = 5.
Thus, the required value of c is 5.